# 50 mA minimum output current
# Output swing (200X load) to
within 1.5V of supplies
(14V pk-pk differential)
# Low power-11 mA typical supply
current
Applications
# Twisted pair driver
# Differential line driver
# VGA over twisted pair
# ADSL/HDSL driver
# Single ended to differential
amplification
# Transmission of analog signals in
a noisy environment
General Description
The EL2140C/2141C is a very high bandwidth amplifier whose
output is in differential form, and is thus primarily targeted for
applications such as driving twisted pair lines, or any application where common mode injection is likely to occur. The input
signal can be in either single-ended or differential form, but the
output is always in differential form.
On the EL2141C, two feedback inputs provide the user with the
ability to set the device gain, (stable at minimum gain of two),
whereas the EL2140C comes with a fixed gain of two.
The output common mode level is set by the reference pin
(V
), which has ab3 dB bandwidth of over 100 MHz. Gen-
REF
erally, this pin is grounded, but it can be tied to any voltage
reference.
The transmission of ADSL/HDSL signals requires very low
distortion amplification, so this amplifier was designed with
this as a primary goal. The actual signal distortion levels depend upon input and output signal amplitude, as well as the
output load impedance. (See distortion data inside.)
Both outputs (V
OUT,VOUTB
) are short circuit protected to
withstand temporary overload condition.
Connection Diagrams
EL2140CEL2141C
Ordering Information
Part No. Temp. Range Package Outline
EL2140CNb40§Ctoa85§C 8-pin PDIP MDP0031
EL2140CSb40§Ctoa85§C 8-pin SOIC MDP0027
EL2141CNb40§Ctoa85§C 8-pin PDIP MDP0031
EL2141CSb40§Ctoa85§C 8-pin SOIC MDP0027
Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a ‘‘controlled document’’. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
Supply Voltage (VCC–VEE)0V–12.6V
Maximum Output Current
Storage Temperature Range
Operating Junction Temperaure
Important Note:
All parameters having Min/Max specifications are guaranteed. The Test Level column indicates the specific device testing actually
performed during production and Quality inspection. Elantec performs most electrical tests using modern high-speed automatic test
equipment, specifically the LTX77 Series system. Unless otherwise noted, all tests are pulsed tests, therefore T
Test LevelTest Procedure
I100% production tested and QA sample tested per QA test plan QCX0002.
II100% production tested at T
IIIQA sample tested per QA test plan QCX0002.
IVParameter is guaranteed (but not tested) by Design and Characterization Data.
VParameter is typical value at T
DC Electrical Characteristics
ea
V
CC
5V, V
EE
T
eb
MAX
5V, T
and T
A
per QA test plan QCX0002.
MIN
e
25§C, V
IN
g
b
A
e
60 mA
65§Ctoa150§C
a
150§C
e
25§C and QA sample tested at T
e
25§C for information purposes only.
A
e
0V, R
L
Recommended Operating Temperature
V
IN,VINB,VREF
V
IN–VINB
e
25§C,
A
200, unless otherwise specified
a
V
0.8V (MIN) to V
EE
ParameterDescriptionMinTypMax
V
supply
I
S
V
OS
I
IN
Z
IN
V
DIFF
A
V
A
VOL
V
CM
V
(200)Output Voltage Swing (200X load, V
OUT
V
(100)Output Voltage Swing (100X Load, V
OUT
V
N
V
REF
V
REFOS
Supply Operating Range (VCC–VEE)
Power Supply Current (No Load)1114ImA
Input Referred Offset Voltage
Input Bias Current (VIN,V
Differential Input Impedance400VkX
Differential Input Range
Voltage Gain (EL2140C) V
Open Loop Voltage Gain (EL2141C)75VdB
Input Common Mode Voltage Range (EL2140C)
Input Referred Voltage Noise36VnV/SHz
Output Voltage Control Range (EL2140C)
Output Offset Relative to V
INB,VREF
e
2V
IN
REF
)
pk-pk
OUT
OUT
to V
to V
) (EL2141C)
OUTB
) (EL2141C)g2.9g3.1IV
OUTB
g
3.0g5.0g6.3IV
b
251040ImV
b
20620ImA
g
2.0g2.3IV
1.951.9852.02IV/V
b
2.6
g
3.4g3.6IV
b
2.5
b60b
a
4.0IV
a
3.3IV
a
25
60ImV
PSRRPower Supply Rejection Ratio6070IdB
I
(min)Minimum Output Current5060ImA
OUT
e
CMRRInput Common Mode Rejection Ratio (EL2140C) V
R
OUT
e
(V
OUT
V
OUTB
e
0V) Output Impedence0.1VX
g
2V6070IdB
CM
TDis0.3inTDis3.7in
2
Page 3
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
AC Electrical Characteristics
ea
V
CC
ParameterDescriptionMinTypMax
BW(b3 dB)
SRDifferential Slewrate800VV/ms
TstlSettling Time to 1%15Vns
GBWGain Bandwidth Product400VMHz
V
REFBW
V
REFSR
THDf1Distortion at 100 kHz (Note 1)
dPDifferential Phase@3.58 MHz0.16V
dGDifferential Gain@3.58 MHz0.24V%
Note 1: Distortion measurement quoted for V
Pin Description
Pin No.
EL2140C EL2141C
12VINNon-inverting Input
3V
43V
55V
66VCCPositive Supply
77VEENegative Supply
88V
eb
5V, V
EE
(b3 dB)V
1FBPNon-inverting Feedback Input. Resistor R1 must be Connected from this Pin to V
4FBNInverting Feedback Input. Resistor R3 must be Connected from this pin to V
e
5V, T
b
REF
V
REF
25§C, V
A
3 dB Bandwidth (EL2140C and EL2141C@gain of 2)150VMHz
b
3 dB Bandwidth130VMHz
Slewrate100VV/ms
Pin NameFunction
INB
REF
OUTB
OUT
e
0V, R
IN
OUT–VOUTB
Inverting Input (EL2140C only)
(EL2141C only)
(EL2141C only)
Output Common-mode Control. The Common-mode Voltage of V
Follow the Voltage on this Pin. Note that on the EL2141, this pin is also the V
Inverting Output
Non-inverting Output
LOAD
e
200, unless otherwise specified
e
12V pk-pk, R
LOAD
e
b
75VdB
200X, Vgaine8.
OUT
Test
Level
and V
OUTB
OUTB
INB
OUT
.
will
pin.
Units
§
TDis2.0in
.
3
Page 4
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves
ISvs Supply Voltage
EL2141 Frequency Response vs
Resistor R2 (GAINe2)
2140-3
EL2140 Frequency Response
Frequency Response
vs Temperature
2140-4
EL2141 Frequency Response vs
Resistor R2 (GAINe8)
2140-5
2140-7
2140-6
EL2141 Distortion vs Frequency
(GAIN
V
IN
e
e
2V pk/pk
6, R
LOAD
e
200X)
2140-8
4
Page 5
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Performance Curves
EL2140 CMRR vs Frequency
Ð Contd.
2140-9
EL2140 V
Frequency Response
REF
EL2141 Output Signal and Common
Mode Signal vs Frequency
2140-10
2140-11
2140-12
EL2140 Small Signal Response (Note 1)
Note 1: Photo shows voltages on a 100X transmission line terminated at both ends, so voltages at V
values shown.
5
OUT,VOUTB
are twice the
Page 6
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Applications Information
EL2141C
2140-13
R1aR2aR3
e
GAIN
R2
Choice of feedback resistor
There is little to be gained from choosing resistor
R2 values below 400X and, in fact, it would only
result in increased power dissipation and signal
distortion. Above 400X, the bandwidth response
will develop some peaking (for a gain of two), but
substantially higher resistor R2 values may be
used for higher voltage gains, such as up to 2 kX
at a gain of eight before peaking will develop. R1
and R3 are selected as needed to set the voltage
gain, and while R1
e
R3 is suggested, the gain
equation above holds for any values (see distortion for further suggestions).
Capacitance considerations
As with many high bandwidth amplifiers, the
EL2140C/2141C prefer not to drive highly capacitive loads. It is best if the capacitance on V
and V
is kept below 10 pF if the user does
OUTB
OUT
not want gain peaking to develop.
In addition, on the EL2141C, the two feedback
nodes FBP and FBN should be laid out so as to
minimize stray capacitance, else an additional
pole will potentially develop in the response with
possible gain peaking.
EL2140C
2140-14
V
OUT
GAINe2
a
V
OUTB
2
e
V
REF
(common mode)
The amount of capacitance tolerated on any of
these nodes in an actual application will also be
dependent on the gain setting and the resistor
values in the feedback network.
Distortion considerations
The harmonics that these amplifiers will potentially produce are the 2nd, 3rd, 5th, and 6th.
Their amplitude is application dependent. All
other harmonics should be negligible by comparison. Each should be considered separately:
H2 The second harmonic arises from the input
stage, and the lower the applied differential signal amplitude, the lower the magnitude of the
second harmonic. For practical considerations of
required output signal and input noise levels, the
user will end up choosing a circuit gain. Referring to Figure 1, it is best if the voltage at the
negative feedback node tracks the V
REF
node,
and the voltage at the positive feedback node
tracks the V
oretically require that R1
the lowest distortion is found at about R3
a
(0.7*R2). With this arrangement, the second
node respectively. This would the-
IN
aR2e
R3, although
e
R1
harmonic should be suppressed well below the
value of the third harmonic.
6
Page 7
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Applications Information
H3 The third harmonic should be the dominant
harmonic and is primarily affected by output
load current which, of course, is unavoidable.
However, this should encourage the user not to
waste current in the gain setting resistors, and to
use values that consume only a small proportion
of the load current, so long as peaking does not
occur. The more load current, the worse the distortion, but depending on the frequency, it may
be possible to reduce the amplifier gain so that
there is more internal gain left to cancel out any
distortion.
Ð Contd.
Typical Applications Circuits
H5 The fifth harmonic should always be below
the third, and will not become significant until
heavy load currents are drawn. Generally, it
should respond to the same efforts applied to reducing the third harmonic.
H6 The sixth harmonic should not be a problem
and is the result of poor power supply decoupling. While 100 nF chip capacitors may be sufficient for some applications, it would be insufficient for driving full signal swings into a twisted
pair line at 100 kHz. Under these conditions, the
addition of 4.7 mF tantalum capacitors would
cure the problem.
Figure 1. Typical Twisted Pair Application
7
2140-15
Page 8
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Figure 2. Dual Coaxial Cable Driver
Figure 3. Single Supply Twisted Pair Driver
Ð Contd.
2140-16
2140-17
8
Page 9
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Figure 4. Differential Line Driver with Equalization
R1aR2aR3
DC Gain
HF Gain
e
e
R2
R1a(R2//R4)aR3
(R2//R4)
(See Figure 5)
(See Figure 5)
Ð Contd.
2140-18
where f
and f
p
e
o
e
2 q C1R
1
2 q C1R
1
4
Figure 5
2140-19
2
9
Page 10
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
Typical Applications Circuits
Figure 6. Dual Signal Transmission Circuit
Ð Contd.
2140-20
10
Page 11
BLANK
11
Page 12
EL2140C/2141C
150 MHz Differential Twisted Pair Driver
EL2140C/2141COctober 1995, Rev A
General Disclaimer
Specifications contained in this data sheet are in effect as of the publication date shown. Elantec, Inc. reserves the right to make changes
in the circuitry or specifications contained herein at any time without notice. Elantec, Inc. assumes no responsibility for the use of any
circuits described herein and makes no representations that they are free from patent infringement.
WARNING Ð Life Support Policy
Elantec, Inc. products are not authorized for and should not be
used within Life Support Systems without the specific written
consent of Elantec, Inc. Life Support systems are equipment in-
Elantec, Inc.
1996 Tarob Court
Milpitas, CA 95035
Telephone: (408) 945-1323
(800) 333-6314
Fax: (408) 945-9305
European Office: 44-71-482-4596
tended to support or sustain life and whose failure to perform
when properly used in accordance with instructions provided can
be reasonably expected to result in significant personal injury or
death. Users contemplating application of Elantec, Inc. products
in Life Support Systems are requested to contact Elantec, Inc.
factory headquarters to establish suitable terms & conditions for
these applications. Elantec, Inc.’s warranty is limited to replacement of defective components and does not cover injury to persons or property or other consequential damages.
Printed in U.S.A.12
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